CBI sources said the seven persons allegedly incited the mob to kill the DSP, who had arrived on the scene after getting information about the murder of village head Nanhe Yadav.

They said one of the person who allegedly led the mob to kill the officer was Bhulle Pal, a security guard with the then State Minister Raja Bhaiya who has been named by the slain officer's wife in her FIR as the main suspect.

The sources said four persons -- son, two brothers and a domestic help of Nanhe Yadav -- have already been arrested in connection with the murder of the DSP on April 13 and the new arrests take the numbers of arrested accused to 11.

Yadav, Saroj, Gautam and Ramashray were associates of village head Nanhe Yadav, who was murdered hours before the killing of the DSP, while Chhote Lal Yadav and Munna Patel were his neighbours.

The sources said the agency is continuing its investigation to probe the larger conspiracy behind the murder of Nanhe Yadav and DSP Zia-ul-Haq. CBI sources claimed Haque, who was posted as Deputy Superintendent of Police at Kunda, had reached the house of Nanhe Yadav after getting the news of his murder on March 2.

By the time he approached the site, the news of Yadav's murder had spread and a large crowd gathered outside his house which was angry at the alleged apathy of the police and protested the police's alleged failure to stop the murder.

The sources said agency has recovered the weapon, allegedly used in the killing Haq.